Up to 12 policemen were killed and 11 others wounded while trying to find the bodies of heads found outside a local slaughter house between Acapulco and Mexico City.
The suspected ambush was set by one of the drug cartels trying to establish control over a region that grows marijuana and opium. The beheading held a warning for La Familia and is suspected to be from the Knights Templar. The two major rivals are fighting for control of the drug-growing region, reported the BBC.
In Sunday's ambush six state and six local policemen were killed. It happened on a road leading out of the town of Teloloapan, between Acapulco and Mexico City, said Arturo Martínez, a Guerrero State police spokesman, according to the Herald Sun.
The area where the ambush took place is close to the area under the influence of La Familia in Michoacan State.
The drug-rich area deploys some 4,000 Mexican police and army that are involved in operations against drug traffickers in the area, trying to safeguard some tourist-friendly locations like Acapulco and Zihuatanejo.
In September 2010, nine police officers were kidnapped in Teloloapan as they were investigating the death of a man in the village of El Revelado. The bodies of eight of the officers were found days later. Six had been dismembered. One officer was found alive, reported the Herald Sun.
Since 2006 the fight between drug cartels and the administration has cost 50,000 lives, with 2,500 of those killed being policemen.